Additional recommended knowledge

Gulonolactone oxidase deficiency

The non-functional GULOP was mapped to human chromosome 8p21 that corresponds to an evolutionarily conserved segment on either porcine chromosome 4 (SSC4) or 14 (SSC14).[1] GULO produces ascorbic acid, which is often called "vitamin C".

Animals that have lost the ability to synthesize vitamin C are, notably: simians (primates), guinea pigs, the red-vented bulbul, fruit-eating bats and a species of trout.[2]

Gulonolactone oxidase deficiency is called "hypoascorbemia"[3] and is described by OMIM (Online Mendelian Inheritance in Man)[4] as "a public inborn error of metabolism", as it affects all humans. There exists a wide discrepancy between the amounts of ascorbic acid other primates consume and what is recommended as "reference intakes" for humans.[5]